How Environmental Pollutants and Genetics Work Together in Rheumatoid Arthritis

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It has been known for more than three decades that individuals with a particular version of a gene — human leukocyte antigen (HLA) — have an increased risk for rheumatoid arthritis.

It has been known for more than three decades that individuals with a particular version of a gene — human leukocyte antigen (HLA) — have an increased risk for rheumatoid arthritis.

Meanwhile, in recent years, there has been a growing interest in the relationship between rheumatoid arthritis and environmental factors, such as cigarette smoking. In smokers who develop rheumatoid arthritis, the disease hits harder. Smokers who also carry the HLA gene variant have even higher likelihood to develop RA, and their disease is more severe. For these patients, this means not only greater pain and swelling, but also more severe bone destruction — a lesser known and more dangerous aspect of the disease.

In a new mouse study, Michigan Medicine researchers probed the relationship between these two factors: the HLA gene and environmental pollutants.

“We found a particular enzyme that acts as a channel, or pathway, in the cell for a conversation between the two culprits, so they work together to do greater damage. Individually they are bad, but together, they’re worse,” says Joseph Holoshitz, M.D., professor of internal medicine and associate chief for research in the Division of Rheumatology at the University of Michigan School of Medicine.

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